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Author Question: How was the style of plate tectonics different in the Archean than it is today? When did the present ... (Read 20 times)

vinney12

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on: Jul 15, 2018

How was the style of plate tectonics different in the Archean than it is today? When did the present
  style of plate tectonics begin? What will be an ideal response?



Question 2

What is the origin of greenstone belts? What will be an ideal response?


Jossy

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Reply #1 on: Jul 15, 2018
Answer to Question 1

Earth in the Archean was much hotter than it is today because Earth's radiogenic heat production was
much higher; in other words, many radiogenic isotopes have decayed to stable daughters and no longer
give off heat. With more heat available, seafloor spreading and plate movements took place more
rapidly. The current plate tectonics style began by the Paleoproterozoic.



Answer to Question 2

Greenstone belts developed in back-arc marginal basins that open and then close. When the basin
opens, volcanism and sedimentation take place, and then the basin closes during a period of
compression. During closure, the rocks are intruded by plutons and metamorphosed, and the
greenstone belt is folded into a syncline and also faulted.



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